The present invention relates to a V-engine with rotatable cylinder heads.
V-engines are generally known in the art. They conventionally have two banks of cylinders each comprising the same number of cylinders. The cylinders are arranged in pairs substantially opposite one another. Thus, a V-engine has in all two or four or six cylinders. However, engines that have more than six cylinders are also known.
The cylinders of the two banks of cylinders are tilted at an angle to one another. This angle is known as the V-angle. On their underside the cylinders are connected to the crankshaft via connecting rods. The V widens out further in the upward direction, so that finally there is enough space to arrange the cylinder heads on the corresponding banks of cylinders.
The inlet valves and the outlet valves and the camshafts that actuate the valves are housed in the cylinder heads. The supply of fuel and the removal of exhaust gas from the cylinders are controlled by the inlet valves and outlet valves. The valves are actuated by the camshaft. The camshaft is driven by the crankshaft by means of a power-transmitting endless element, conventionally a chain or a belt.
As a rule, one inlet valve and one outlet valve are provided for each cylinder. However, it is also known to provide more than one inlet valve and one outlet valve. Either the inlet valves and the outlet valves of one bank of cylinders may be controlled jointly by one camshaft, or two camshafts may be provided, one of which controls the inlet valves while the other controls the outlet valves.
Depending on the dimensions of the cylinders and cylinder heads, the V-angle is limited in the downward direction but may be up to 180°.
In order to make the engine as small as possible in construction, the V-angle is frequently selected so that components of the engine can be arranged inside the V. As it has proved advantageous when arranging the inlet valves and outlet valves to place the valves opposite one another on opposite sides of the cylinder head, so that there is a crossflow of fresh and exhaust gas inside the combustion chamber of the cylinder, the air/fuel supply system is nowadays often arranged inside the V. The exhaust gas system is then arranged accordingly on the outer sides of the banks of cylinders.
In some cases it may also be advantageous to arrange the exhaust gas system inside the V and to arrange the air/fuel supply system on the outside of the cylinder heads. This arrangement can significantly improve the efficiency of V-engines particularly with respect to the efficient use of turbochargers.
A special cylinder head may be provided for each bank of cylinders. This means that there is one cylinder head for the “right-hand” bank of cylinders and one cylinder head for the “left-hand” bank of cylinders. This type of construction has the advantage that when designing the connections and attachments of the cylinder heads to the other engine components, there is no need to be concerned with maintaining a symmetrical arrangement etc. One disadvantage, however, is the fact that the two cylinder heads have different components, which increases the production costs.
In order to achieve greater economy in V-engine production, V-engines have been developed which are symmetrically constructed such that the cylinder heads are identical, i.e. the cylinder heads are identical components. In this way, errors during assembly are prevented and the production costs of the engine are reduced.
As already mentioned, in V-engines of the prior art, the exhaust gas system is generally guided outwards and the air/fuel supply system is generally guided within the V. Under certain circumstances it may also be advantageous to guide the exhaust gas system inside the V and the fuel supply system outside. The V-engines according to the prior art cannot, however, be used for both types of arrangement. The engines are designed only for one or other type of arrangement. If a different one is wanted, a new construction is required, which incurs considerable costs.